It is well-known that a high current electrical connection is very dangerous and may cause a person to be critically injured. Electrocution is a major concern for not only children and adults at home but also for many industrial workers. Due to the size of high current socket contacts in industrial plants, it is easy for a person to poke a finger or other objects into a socket opening and touch electrically-live metal components within the socket. There have been numerous efforts to overcome this problem as outlined in the following patents:
U.S. Pat. No. 5,113,045 Crofton PA1 U.S. Pat. No. 5,069,632 Avitan PA1 U.S. Pat. No. 5,147,988 Appleton PA1 U.S. Pat. No. 5,256,076 Hamlin PA1 U.S. Pat. No. 4,148,536 Petropoulos PA1 U.S. Pat. No. 5,586,646 Bridgeman PA1 U.S. Pat. No. 5,112,237 Yang PA1 U.S. Pat. No. 5,095,182 Thompson PA1 U.S. Pat. No. 4,652,067 Lutzenberg PA1 U.S. Pat. No. 5,186,639 Comerci
As discussed in greater detail below, the preponderance of prior art concentrates on enhancing safety at home and not at the workplace. Several prior art socket arrangements are disclosed which incorporate devices and structures for avoiding accidents at home but the prior art generally neglects the problem of protecting industrial workers from electrocution.
U.S. Pat. No. 5,113,045, entitled Safety Outlet, describes a safety outlet which requires male prongs to force a pair of plungers into making contact with a pair of switches. The prongs are inserted into the outlet in order to depress the plungers which, in turn, closes the switches and initiates a supply of current to the prongs. The plungers are positioned in a manner by which the insertion of foreign objects will not exert enough pressure to depress the plungers. This is the safety feature of the outlet.
U.S. Pat. No. 5,069,632, entitled Electrical Supply Safety Socket, describes a safety socket which is activated only when female socket outlets are forced into contact with energized components by insertion of a plug. Insertion of the plug activates a spring-biased switch which biases two armatures between open and closed positions. The armatures are articulated to a pivotally mounted support in order for them to be displaceable toward and away from each other. This prior art device also reduces the chance of electrocution by requiring two objects to be inserted in order to overcome both the spring-biased switch and the contact armatures.
U.S. Pat. No. 5,147,988, entitled Switching Electrical Receptacle, describes a power receptacle having a housing with sliding contacts of cylindrical symmetry which can be manually engaged. The housing slides into and out of an electrical connection with female contacts in order to make or break a circuit. The female contacts are connected to load terminals.
U.S. Pat. No. 5,256,076, entitled Safety Electrical Receptacle, describes a receptacle which does not allow current flow until switches are closed by an inserted plug. The plug depresses an operating lever which, in turn, creates a connection between movable and fixed contacts. According to one embodiment, the plugs contain special posts in order to activate the switches. In another embodiment, the grounding tine is used to close switches which help transmit electrical energy to output wiring.
U.S. Pat. No. 4,148,536, entitled Safety Electrical Receptacle, describes a receptacle which only operates when its female contacts are energized after the insertion of prongs. The prongs push an insulative member in order to establish a connection between a contact arm and a power line connector.
U.S. Pat. No. 5,586,646, entitled Vehicle Locking System, describes a sliding contact linear switch. A system is disclosed which uses an actuator plunger, shiftable between two positions to lock and unlock a vehicular door.
U.S. Pat. No. 5,112,237, entitled Safety Plug Receptacle, describes a receptacle which requires the body of a male plug to depress its spring loaded pin in order to engage an internal switch. The switch turns on a LED to notify the user that a connection is made. This prior art device prevents the possibility of short circuiting wires.
U.S. Pat. No. 5,095,182, entitled Shockproof Safety Outlet, describes a socket with two blade slots which prevents users from receiving shocks. The longer of the two blades is used to activate the supply current.
U.S. Pat. No. 4,652,067, entitled Electrical Connector with an Internal Switch, describes an electrical connector whose plunger is operable by the body of a male contact during insertion. Depending on the presence or lack of presence of a plug, the internal switch moves the plunger to open and closed positions.
U.S. Pat. No. 5,186,639, entitled Electrical Connector with Plug Detection Switch, describes the use of a switch mechanism to detect the presence of a fully inserted plug and then produces a supply current.